Rear Speaker

[CanalDigger]

Hi from a Newbie,
I'm refitting the Ford Radio in a 2010 build, Mk7 Transit based Motorhome, so to the rear of the B Pillar there is very little 'Ford' above chassis. Previous owner fitted a modern Kenwood radio (anybody want it?), with speakers behind the roof lining somewhere near the top of the plastic trim around seatbelts etc (a good part of the reason for the poor sound from the Kenwood?) rather than use the door speakers. Having refitted a Ford 6000 Radio, I hoping that I can use these speakers as the rear pair if I install them better. My question is where would I find the ends of the wires that start at the plug on the back of the radio, yes I know that I could splice into them there. Please does anyone know what the impedance & wattage of the Ford Rear Speakers is? Please does anyone have a spare radio cage?
Other jobs to do:
1. Behind the Kenwood there were 2(!) Adaptor Cable/ Plug Sets (the sort you can buy in Halfords). Apart from other remains [filter, amplifier] only part installed, there are 2 two core cables going somewhere.
2. I want to fit glovebox, footwell & cabdoor step lights and DRLs